This invention relates to a composition of a dispersing agent or dispersant for cement which is highly dispersible and low in foamablity, and a method for preparing the same. More particularly, it is concerned with an improved dispersant, in which a mixture of hydrocarbon compounds of high aromaticity obtained by heat-treating at a high temperature raw material hydrocarbon from petroleum or coal is subjected to sulfonation, and the sulfonated compound is then neutralized.
In general, a dispersing agent is effective in dispersing oil or fine particles of a solid substance into water. Most of the dispersing agents known heretofore, however, cause considerable foaming by agitation at the time of dispersion, or entrain air into the dispersion liquid to incorporate within the liquid numerous fine foams. While such foaming effect may, in some cases, be effectively utilized, it becomes very often a great problem. For example, a layer of foam on the surface of a liquid shields the liquid phase from the external atmosphere, which prevents the liquid from contacting the external atmosphere and makes it difficult to observe the condition of the liquid surface. This foaming phenomenon, therefore, constitutes a considerable obstacle in the practical aspect. Another disadvantage arising from such foaming is that, in the field of ceramics industry where slurry or paste prepared by dispersing powder particles of a solid material into water is used, the layer of foam created on the liquid surface impairs moldability of the slurry or pasty material, or the foams created by entrained air in the dispersion result in molded articles of high porosity, lowering the mechanical strength of the shaped products.
Under the circumstances, it has been the long-felt need that an improved dispersing agent which is causes less foaming and possesses excellent dispersibility be developed.